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/*
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 * Copyright (c) 2004 World Wide Web Consortium,
 *
 * (Massachusetts Institute of Technology, European Research Consortium for
 * Informatics and Mathematics, Keio University). All Rights Reserved. This
 * work is distributed under the W3C(r) Software License [1] in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 */

package org.w3c.dom.ls;

/**
 * <code>LSResourceResolver</code> provides a way for applications to redirect references to
 * external resources. <p> Applications needing to implement custom handling for external resources
 * can implement this interface and register their implementation by setting the "resource-resolver"
 * parameter of <code>DOMConfiguration</code> objects attached to <code>LSParser</code> and
 * <code>LSSerializer</code>. It can also be register on <code>DOMConfiguration</code> objects
 * attached to <code>Document</code> if the "LS" feature is supported. <p> The <code>LSParser</code>
 * will then allow the application to intercept any external entities, including the external DTD
 * subset and external parameter entities, before including them. The top-level document entity is
 * never passed to the <code>resolveResource</code> method. <p> Many DOM applications will not need
 * to implement this interface, but it will be especially useful for applications that build XML
 * documents from databases or other specialized input sources, or for applications that use URNs.
 * <p ><b>Note:</b>  <code>LSResourceResolver</code> is based on the SAX2 [<a
 * href='http://www.saxproject.org/'>SAX</a>] <code>EntityResolver</code> interface. <p>See also the
 * <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-LS-20040407'>Document Object Model (DOM) Level
 * 3 Load and Save Specification</a>.
 */
public interface LSResourceResolver {

  /**
   * Allow the application to resolve external resources.
   * <br> The <code>LSParser</code> will call this method before opening any
   * external resource, including the external DTD subset, external
   * entities referenced within the DTD, and external entities referenced
   * within the document element (however, the top-level document entity
   * is not passed to this method). The application may then request that
   * the <code>LSParser</code> resolve the external resource itself, that
   * it use an alternative URI, or that it use an entirely different input
   * source.
   * <br> Application writers can use this method to redirect external
   * system identifiers to secure and/or local URI, to look up public
   * identifiers in a catalogue, or to read an entity from a database or
   * other input source (including, for example, a dialog box).
   *
   * @param type The type of the resource being resolved. For XML [<a
   * href='http://www.w3.org/TR/2004/REC-xml-20040204'>XML 1.0</a>] resources (i.e. entities),
   * applications must use the value <code>"http://www.w3.org/TR/REC-xml"</code>. For XML Schema [<a
   * href='http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/'>XML Schema Part 1</a>] ,
   * applications must use the value <code>"http://www.w3.org/2001/XMLSchema"</code>. Other types of
   * resources are outside the scope of this specification and therefore should recommend an
   * absolute URI in order to use this method.
   * @param namespaceURI The namespace of the resource being resolved, e.g. the target namespace of
   * the XML Schema [<a href='http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/'>XML Schema Part
   * 1</a>] when resolving XML Schema resources.
   * @param publicId The public identifier of the external entity being referenced, or
   * <code>null</code> if no public identifier was supplied or if the resource is not an entity.
   * @param systemId The system identifier, a URI reference [<a href='http://www.ietf.org/rfc/rfc2396.txt'>IETF
   * RFC 2396</a>], of the external resource being referenced, or <code>null</code> if no system
   * identifier was supplied.
   * @param baseURI The absolute base URI of the resource being parsed, or <code>null</code> if
   * there is no base URI.
   * @return A <code>LSInput</code> object describing the new input source, or <code>null</code> to
   * request that the parser open a regular URI connection to the resource.
   */
  public LSInput resolveResource(String type,
      String namespaceURI,
      String publicId,
      String systemId,
      String baseURI);

}
